The present invention relates generally to seam plates for use in connection with the retention of roof decking membranes upon roof decking substructures at seam locations defined between separate, adjacent, and overlapping membrane members, and more particularly to a new and improved seam plate, and a roof decking system employing the same, wherein improved retention of the membrane member upon the roof decking substructure is able to be achieved without generating or initiating tearing or other similar deterioration of the roof decking membrane when the membrane is subjected to wind or other environmental forces.
Stress plates or seam plates are used in connection with the retention of roof decking membranes upon roof decking substructures at seam locations defined between separate but adjacent or overlapping membrane members, and are of course well-known in the art. Examples of such seam plates or stress plates are disclosed within U.S. Pat. No. 4,945,699 which issued to Colin R. Murphy on Aug. 7, 1990, as well as U.S. Pat. No. 4,787,188 which also issued to Colin R. Murphy on Nov. 29, 1988. As can be appreciated from FIGS. 1,2, and 3A-3C of the drawings, which substantially correspond to FIGS. 4,1, and 3A-3C, respectively, of the aforenoted U.S. Pat. No. 4,945,699 patent to Murphy, the roof decking substructure is disclosed at 103 and may conventionally be provided with overlying insulation 102. The insulation 102 is, in turn, adapted to have membranes disposed thereon in an overlying manner, and at a location or site at which separate and adjacent membranes are to be in effect seamed together in an overlapping manner, a first underlying membrane is disclosed at 101 and is adapted to be secured to the underlying deck substructure 103 by means of a screw fastener 107 passing through a seam plate or stress plate 10, while a second membrane member 104 is adapted to be secured in an overlapping manner upon the first underlying membrane member 101 by means of a welded seam 111.
The seam plate or stress plate 10 is seen to have a circular configuration, and is provided with an upper surface 11 and a lower surface 12. A central aperture 15 is provided for passage therethrough of the screw fastener 107, and a circular reinforcing rib 14 annularly surrounds the central aperture 15. Accordingly, when such a stress plate or seam plate 10 is to be used to secure membrane members to the underlying decking substructure 103, the stress plate or seam plate 10 is disposed atop the first underlying membrane member 101, and the stress plate or seam plate 10 is then fixedly secured to the underlying decking substructure by means of screw fastener 107 being threadedly engaged with the underlying decking substructure. In accordance with the particularly unique stress plate or seam plate 10 as disclosed with the noted Murphy patents, the bottom surface 12 of the stress plate or seam plate 10 is provided with a plurality of circumferentially spaced prongs or tangs 21 each of which terminates in a gripping point 22. The prongs or tangs 21 each have a substantially triangular configuration and are in effect partially punched-out or otherwise cut from the bottom surface portion 12 of the plate 10, and are subsequently bent such that the prongs or tangs 21 attain their desired disposition with respect to the bottom surface portion 12 of the plate 10. Such prongs or tangs 21 will therefore grip the lower or underlying membrane sheet 101 and prevent the same from becoming loose or free with respect to the stress plate 10 or the underlying roof substructure 103 despite wind or other environmental forces being impressed upon the membrane sheet 101.
While the aforenoted stress or seam plates of Murphy have been satisfactory and commercially successful, it has been experienced that, despite well-meaning statements of intent to the contrary as set forth in the Murphy patents, the presence of the pointed prongs or tangs 21 characteristic of the stress plate or seam plate 10 of Murphy do in fact tend to puncture, tear, weaken, and otherwise cause deterioration of the membrane sheets 101 under wind and other environmental conditions. Obviously, such a state is not satisfactory in view of the fact that eventually, the membrane sheets tear away from the overlying seam plate 10 as well as away from the underlying roof decking, with the consequent result being the compromise of the structural integrity of the entire roof decking system.
A need therefore exists in the art for a new and improved stress plate or seam plate wherein the plate can satisfactorily engage the membrane sheets so as to secure the membrane sheets to the underlying decking substructure, and yet, the means formed upon the stress plate or seam plate for engaging the membrane sheets will not tend to initiate tearing of the membrane sheets and thereby cause separation of the sheets with respect to the stress plate or seam plate as well as the underlying decking substructure under, for example, windy or other forceful environmental conditions.
Accordingly, it is an object of the present invention to provide a new and improved stress plate or seam plate for use in connection with the fixing or securing of membrane sheets to underlying roof decking substructures.
Another object of the present invention is to provide a new and improved stress plate or seam plate for use in connection with the fixing or securing of membrane sheets to underlying roof decking substructures wherein the stress plate or seam plate effectively overcomes the various operational disadvantages or drawbacks characteristic of conventional stress plates or seam plates.
An additional object of the present invention is to provide a new and improved stress plate or seam plate for use in connection with the fixing or securing of membrane sheets to underlying roof decking substructures wherein the stress plate or seam plate effectively overcomes the various operational disadvantages or drawbacks characteristic of conventional stress plates or seam plates by providing the stress plate or seam plate with a plurality of circumferentially spaced, downwardly extending, triangularly configured projections wherein, in lieu of the projections having sharp pointed apex portions, the projections have substantially rounded or radiused apex portions so as not to in fact cause or initiate tearing or rupture of the roof decking membrane sheets under wind or other environmental force conditions.
A further object of the present invention is to provide a new and improved stress plate or seam plate for use in connection with the fixing or securing of membrane sheets to underlying roof decking substructures wherein the stress plate or seam plate effectively overcomes the various operational disadvantages or drawbacks characteristic of conventional stress plates or seam plates by providing the stress plate or seam plate with a plurality of circumferentially spaced, downwardly extending, triangularly configured projections wherein, in lieu of the projections having sharp pointed apex portions, the projections have substantially rounded or radiused apex portions so as not to in fact cause or initiate tearing or rupture of the roof decking membrane sheets under wind or other environmental force conditions, and wherein further, the seam plate or stress plate is also provided with different annular or circular rib structure which imparts various reinforcing and bending or flexibility characteristics to the stress plate or seam plate, as functions of or with respect to the characteristics of the membrane sheets, under such aforenoted wind or other environmental force conditions.
A last object of the present invention is to provide a new and improved stress plate or seam plate for use in connection with the fixing or securing of membrane sheets to underlying roof decking substructures wherein the stress plate or seam plate effectively overcomes the various operational disadvantages or drawbacks characteristic of conventional stress plates or seam plates by providing the stress plate or seam plate with a plurality of circumferentially spaced, downwardly extending, triangularly configured projections wherein, in lieu of the projections having sharp pointed apex portions, the projections have substantially rounded or radiused apex portions so as not to in fact cause or initiate tearing or rupture of the roof decking membrane sheets under wind or other environmental force conditions, and wherein further, the seam plate or stress plate is also provided with different annular or circular rib structure which imparts various reinforcing and bending or flexibility characteristics to the stress plate or seam plate, as functions of or with respect to the characteristics of the membrane sheets, under such aforenoted wind or other environmental force conditions, the various dimensions or extents of the projections and rib structure being capable of being tailored to fit various operational parameters characteristic of the different membrane sheets being employed so as to be operationally compatible therewith.
The foregoing and other objectives are achieved in accordance with the teachings and principles of the present invention through the provision of a new and improved stress plate or seam plate which comprises a circular structure having a central aperture for receiving a screw fastener. A downwardly projecting annular rib surrounds the central aperture for reinforcing the same, and a plurality of concentric ribs are defined between the central aperture and the peripheral edge of the plate for providing reinforcing and bending or flexibility characteristics to the stress plate or seam plate. The width, height, and shape of the concentric ribs can be varied as functions of the structural parameters or characteristics of the membrane sheets. In addition, in accordance with particularly unique and novel structure provided upon the stress plate or seam plate in accordance with the principles and teachings of the present invention, a plurality of circumferentially spaced, downwardly extending projections having substantially V-shaped cross-sectional configurations are provided upon the underside of the seam or stress plate. Contrary to the PRIOR ART stress plate having the sharp-pointed prongs or tangs provided thereon, the projections of the present invention have substantially rounded or radiused apices so as not to puncture or rupture the membrane sheets, and yet such projections can satisfactorily engage the membrane sheets so as to fixedly retain the same upon the underlying roofing deck substructural assembly. As was the case with the concentric rib structure, the width of the various projections can be varied depending upon the particular structural parameters or characteristics of the membrane sheets being used.